The 32-year-old Frandsen chose to become a free agent after being optioned to the minors by Philadelphia last weekend.

He has big league experience at all four infield positions and led the majors in pinch hits with 14 for the Phillies in 2013.

Frandsen is a career .259 hitter in seven seasons with the Phillies, Angels and Giants.

"It's important for your team to have guys that can move around and that are experienced in that regard and have done it," Washington manager Matt Williams said before his team's 3-2 loss to the St. Louis Cardinals on Wednesday.

To make room on their 40-man roster for Frandsen, the Nationals voided their previous option of right-hander Ross Ohlendorf and put him on the 60-day disabled list with a right lumbar strain.